To be honest for me it's less about the actual benefits for it (since I do agree with drawback and limitations). Sure it would be nice to make my toxic planet have 125% hazard rating instead of the current 150% hazard rating if I could turn it into a desert planet and therefore give it the habitable modifier (Since it would at least be a little bit more habitable. even if its a scorching furnace.. Think Tatooine?)
Mostly it's about the aesthetics for me, the RP. I mean, I removed the toxic atmosphere? It shouldn't be a toxic world anymore right? It would either be completely barren, barren-desert, or just a desert. With no change to the Extreme heat modifier, and with or without the habitable trait.
As for the Extreme Cold modifier.. well I don't really have a planet in mind there aside from Frozen I guess or just Barren, Since Tundra wouldn't make sense. There'd be no liquid water anywhere on the surface after all, so no vegetation aside from whatever is under the ice. (Barotrauma flashbacks)
But then, terraforming a frozen world doesn't quite make sense unless you somehow manage to melt all the ice.. which would leave you with a massive ball of water with a rocky core I suppose but.. Doesn't seem possible. same with a Cryovolcanic one. As with a regular volcanic one? Whilst I do say it's easier to terraform those.... it isn't within the time frame we're seeing with the other planets. Sure you could chuck a ton of water-ice asteroids down on it and start the same process Earth went through billions of years ago but.. that process would take hundreds if not thousands of years to come to fruition.
Am I making sense?
In either case I love this mod, it's 100% a must have for any run. I made 1 system with 5 planets (1 being a desert planet) end up with a Terran world, a Tundra world, a mining station and the before mentioned toxic world. Still got two more barren planets to go. And I love it to bits.